Continuous flow grain drying apparatus

ABSTRACT

Continuous flow grain drying apparatus having an upper, foraminous drying enclosure into which grain to be dried is introduced and which communicates with a lower, foraminous cooling enclosure. A first enclosed, foraminous duct in the upper enclosure defines therewith a first pair of passages which divide the downward flow of grain into two separate parallel streams, a blower and burner combination communicating with the first duct causing outward flow of heated air simultaneously through the first passages. A second, enclosed, foraminous duct is provided in the lower enclosure defining therewith a second pair of passages and a divider connects the first and second ducts and extends through the open ends of the upper and lower enclosures thereby coupling respective ones of the first and second passages so that the two streams respectively continue separate, downward, parallel flow through the second passages. A blower communicates with the second duct causing an outward flow of cooling air simultaneously through the second passages. The two streams of grain are discharged, separately, from the bottom of the lower enclosure.

United States Patent 1191 Keirn [4 1 Mar. 11, 1975 [76] Inventor: Robert E. Keirn, RR. No. 2, North Manchester, Ind. 46962 [22] Filed: Sept. 13, 1973 [21] Appl. No.: 397,068

Related U.S. Application Data [63] Continuation-impart of Ser. No. 230,857, March 1,

1972, abandoned.

[52] U.S. Cl 34/174, 34/65, 34/171 [51] Int. Cl. F26b 19/00 [58] Field 01' Search 34/56, 6466, 34/165-174 156] References Cited UNITED STATES PATENTS 1,558,119 10/1925 Sherban 34/174 2,740,204 4/1956 Seltzer et al7 3,053,522 9/1962 Applegate 34/174 3,097,934 7/1963 Applegate 3,313,040 4/1967 Mathews 3,406,463 10/1968 Andersen 3,526,969 9/1970 Alms et a1 34/174 FOREIGN PATENTS OR APPLICATIONS 326,871 3/1930 Great Britain 34/171 Primary Examiner.1ohn J. Camby Assistant Examiner-James C. Yeung [57] ABSTRACT Continuous flow grain drying apparatus having an up per, foraminous drying enclosure into which grain to be dried is introduced and which communicates with a lower, foraminous cooling enclosure. A first enclosed, foraminous duct in the upper enclosure defines therewith a first pair of passages which divide the downward flow of grain into two separate parallel streams, a blower and burner combination communicating with the first duct causing outward flow of heated air simultaneously through the first passages. A second, enclosed, foraminous duct is provided in the lower enclosure defining therewith a second pair of passages and a divider connects the first and second ducts and extends through the open ends of the upper and lower enclosures thereby coupling respective ones of the first and second passages so that the two streams re spectively continue separate, downward, parallel flow through the second passages. A blower communicates with the second duct causing an outward flow of cooling air simultaneously through the second passages. The two streams of grain are discharged, separately, from the bottom of the lower enclosure.

3 Claims, 2 Drawing Figures PATENHEW 1 3,869,809

SHEET 2 BF 2 SPEED CONTROL CONTINUOUS FLOW GRAIN DRYING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention A present invention relates generally to continuous flow grain drying apparatus. This application is a continuation-in-part of application Ser. No. 230,857, filed Mar. 1, 1972 now abandoned.

2. DESCRIPTION OF THE PRIOR ART In the storage of grain such as corn, it is a common practice to dry the grain to remove a portion of the moisture content thereof. Many types of batch-type and continuous flow grain drying apparatus have been proposed and used. Typically, such prior grain drying apparatus included one or more chambers arranged to permit a flow of grain to gravitate downwardly therethrough, the grain being first subjected to a flow of heated, dry air which removes moisture and thereafter is subjected to a flow of cool air so as to cool the grain.

In one type of prior grain drying apparatus, the grain is passed through the apparatus in a single, relatively large column thus requiring the use of a multiplicity of air inlet and outlet ducts in order to minimize the length of the air flow paths through the grain. Further, passing the grain through the drying apparatus in a single column results in some portion of the grain be subjected to more or less heating and cooling than other portions.

U.S. Pat. No. 3,526,969 to Erhard E. Alms and James E. Mitchell discloses batch-type grain drying apparatus having separate drying and cooling chambers. Batchtype grain drying apparatus of the type shown in the aforesaid Alms et al patent for employing only a drying chamber is has also been used.

British Pat. No. 326,871 discloses continuous flow grain drying apparatus employing counter-flow of drying air.

In certain installations, by reason of its increased capacity, continuous flow grain drying apparatus is preferred to the batch-type apparatus. Since there are many existent installations of batch-type drying apparatus of the type shown in the aforesaid Alms et al patent, it is desirable to convert such batch-type apparatus to continuous flow apparatus.

SUMMARY OF THE INVENTION The apparatus of the present invention employs the drying chamber portion of batch-type drying appara tus, such as that shown in the aforesaid Alms et al patent, eliminating the holding bin and cooling chamber, if any, and adding thereto a new cooling chamber with flow dividing means in the drying and cooling chambers providing a pair of passages therethrough thus dividing the downward flow of grain into two separate, parallel streams.

In its broader aspects, the continuous flow grain drying apparatus of the invention comprises an upper, foraminous drying enclosure having an top end and an open bottom end with means for introducing grain to be dried to the upper enclosure adjacent its top end for downward gravity flow therethrough. First, enclosed, foraminous duct means is provided in the upper enclosure for defining therewith a first pair of passages therein which divide the downward flow into two separate, parallel streams, and means are provided communicating with the first duct means for causing an outward flow of heated air simultaneously through the first passages. A lower, foraminous cooling enclosure is provided having an open top end connected to the bottom end of the upper enclosure and having a bottom end, and second enclosed, foraminous duct means is provided in the lower enclosure for defining therewith a second pair of passages therein. Divider means is provided' connecting the first and second duct means and extending through the open ends of the enclosures for coupling respective ones of the first and second passages so that the two streams respectively continue separate, downward, parallel flow through the second passages. Means are provided communicating with the second duct means for causing an outward flow of cooling air simultaneously through the second passages. and means are also provided adjacent the bottom end of the lower enclosure for respectively, separately discharging the streams from the second passages whereby the two streams are maintained separate without co-mingling throughout their downward flow through the apparatus.

It is therefore an object of the invention to provide improved continuous flow grain drying apparatus.

Another object of the invention is to provide improved continuous flow grain drying apparatus wherein two separate, parallel streams of grain flow therethrough.

The above-mentioned and other features and object of this invention and the manner of attaining them will become more apparentand the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the improved continuous flow grain drying apparatus of the invention; and

flow grain drying apparatus of FIG. 1, partly in cross section and partly broken away, taken generally along the line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the improved continuous flow grain drying apparatus of the invention, generally indicated at 10, comprises an upper, drying enclosure, generally indicated at 12 and a lower, cooling enclosure generally indicated at 14. Upper enclosure 12 includes a generally cylinderical side wall 16 fabricated from foraminous sheet material, such a perforated steel, having a multiplicity of openings 17 therein. The top end portion of side wall 16 has a longitudinally extending protuberance portion 18, and the entire side wall 16 is reinforced with a plurality of peripherally extending, longitudinally spaced-apart ribs 20. End walls 28, 30 join side wall 16 and complete enclosure 12. Inlet opening 22 is formed in protuberance 18 adjacent end wall 28 and accumulator hopper or storage bin 24 communicates therewith, grain being introduced to upper enclosure 12 through hopper 24 and inlet opening 22, as shown by arrow 25.

Helical loading auger 26 extends longitudinally within protuberance portion 18 being rotatably mounted by bearings 32, 34 in end walls 28, 30. Motor 46 drives auger 26 as by belt drive 50. Distribution FIG. 2 is a fragmentary side view of the continuous trough 52 is mounted vertically beneath and closely adjacent auger 26. The direction of auger 26 is such that grain introduced thereto through inlet opening 22 is moved from right to left as viewed in FIG. 2, as shown by arrow 97, and is distributed into upper enclosure 28 throughout the length thereof, as shown by arrows 54.

A first cylindrical duct 60 is mounted coaxially within upper enclosure 12 extending between end walls 28, 30, duct 60 also being fabricated of foraminous sheet material and having a multiplicity of openings 62 therein. Duct 60 defines two passages 64, 66 with side wall 16 of enclosure 12 thereby dividing the downward flow of grain into two separate, parallel streams, as shown by arrows 68.

Conventional blower-heater units 70 are mounted on end wall 30 communicating with the interior of duct 60 through openings 72 in end wall 30. Blower-heater units 70 thus force heated air into duct 70 and outwardly through opening 62 therein, across passages 64, and outwardly through openings 17 in side wall 16 of enclosure 12, as shown by arrows 73, the flow of heated air simultaneously through passages 64, 66 thus heating and drying the parallel streams of downwardly flowing grain therein.

The bottom end of side wall 16 of upper enclosure 12 has longitudinally extending opening 74 formed therein. Lower, cooling enclosure 14 has a generally diamond-shaped cross-section and includes outer side wall 80 fabricated from foraminous sheet material having a multiplicity of openings 81 therein. End walls 28, 30 are common to upper and lower enclosures 12, 14. Side wall 80 is supported by a plurality of peripherally extending, longitudinally spaced-apart ribs 82. Lower enclosure 14 has longitudinally extending inlet opening 83 formed therein communicating with discharge opening 74 of upper enclosure 12.

A second duct 84 also having a diamond-shaped cross-section is provided within lower enclosure 14 extending between side walls 28, 30 and is formed of foraminous sheet material having a multiplicity of openings 85 therein. Duct 84 defines passages 86, 88 with side wall 80 of lower enclosure 14.

Vertically extending, imperforate divider plate 136 extends between top apex 132 of duct 84 and the bottom portion of duct 60, divider plate 136 extending vertically through openings 74, 83 and extending longitudinally between end walls 28, 30. Divider plate 136 thus bisects openings 74, 83 so as directly to connect passages 64, 86 and 66, 88 so that the two, parallel streams of grain 68, 69 in passages 64, 66 of upper enclosure 12 are maintained separate and continue downward gravity flow as separate parallel streams in passages 86, 88 of lower enclosure 14, as indicated by arrows 90, 91 and 92, 93.

Conventional blower assembly 144 is mounted on end wall 30 and communicates with the interior of duct 84 through opening 140 and end wall 30. Blower assembly 144 forces cool, ambient air into the interior of duct 84, outwardly through openings 85, across passages 86, 88, and outwardly through openings 81, as shown by arrows 142, the simultaneous flow of air through passages 86 cooling the parallel streams of grain flowing therethrough.

Another vertically extending. imperforate divider plate 98 extends between lower apex 100 of duct 84 and lower apex I02 of side wall 80 of lower enclosure 14, divider plate 98 extending longitudinally between end walls 28, 30. Discharge openings 104, 106 are formed in side wall of lower enclosure 14 adjacent bottom apex 102 respectively on opposite sides of divider plate 98 and respectively communicating with passages 86, 88, the separate, downwardly flowing. parallel streams of grain in passages 86, 88 of lower enclosure 14 being separately discharged through openings 104, 106. Flow control gates 108 are provided for respectively selectively adjusting the size of discharge openings 104, 106.

A pair of skirt elements 157, 159 depend from bottom apex of duct 84 in spaced parallel relationship with divider plate 98 and extending longitudinally between end walls 28, 30. The width of skirts 157, 159 is substantially less than the width of divider plate 98. Openings 160 in duct 84 communicate with the spaces between skirts 157, 159 and divider plate 98. Upper and lower enclosures l2, 14 are supported by frame work indicated generally at 131.

Flat plate member 110 extends longitudinally beneath discharge openings 104, 106 on either side of divider plate 98. Metering rolls 126 are positioned beneath discharge openings 104, 106, above plate 110, and on either side of divider plate 98 for respectively metering the grain discharged through openings 104, 106. A pair of discharge augers 112 are respectively located in troughs 114 which are respectively attached to the side edges 116 of plate 110, discharge augers 112 receive grain respectively metered by metering rolls 126 from discharge openings 104, 106 and are rotated in a direction to move the grain from right to left as viewed in FIG. 2, as shown by arrow 118, for ultimate discharge through conduit 120. Discharge augers 112 are driven by a suitable drive motor 122.

Metering rolls 126 are.driven by a suitable variable speed motor 124, the speed of which is controlled by conventional speed control apparatus 128.

A moisture sensing device 130, such as a humidistat, is positioned in hopper 24 for sensing the moisture content of the grain entering the apparatus. Moisture sensing device is electrically coupled to speed control device 128 by suitable electrical leads 132, speed control device 128 controlling the speed of metering rolls 128 in inverse proportional to the moisture content of the entering grain, i.e., as the moisture content of the entering grain increases, the speed of the metering rolls is decreased. Moisture sensing device 130 may alternatively be located in one of the passages 64, 66 of upper enclosure 12, as shown in dashed lines at 130a.

In converting batch-type grain drying apparatus of the type shown in the aforesaid Alms et al patent to the continuous flow apparatus described above, the holding bin of the batch-type apparatus, if present, is eliminated, small hopper 24 installed, and distributing auger 26 installed. The lower cooling chamber, if present, is removed (and may be used as the drying chamber for another continuous flow dryer) and the drying chamber is elevated as need be. Divider plate 136 is then installed followed by installation of lower enclosure 80 having duct 84 and divider plate 98 therein, together with metering rolls 126, unloading augers 112, and the associated drive and control apparatus.

ln the operation of continuous flow grain drying apparatus 10, grain is continuously fed into the upper drying enclosure 12 through hopper 24 and inlet opening 22, the grain being longitudinally moved and discharged into upper enclosure 12 by loading auger 26 which substantially and uniformly distributes the grain over the longitudinal length of upper enclosure 12. The grain then passes downwardly by gravity and is divided into two separate and substantially equal streams in passages 64, 66, as shown by arrows 68, 69. Heated drying air is forced by blower-heater assemblies 70 simultaneously outwardly through passages 64, 66 thereby heating and drying the two separate, downwardly flowing streams of grain therein, as indicated by arrows 73. It will be observed that the grain travels a substantial distance as it follows the parallel paths 64, 66 and that the path the drying air must traverse in passing through the grain is relatively short and thus, a relatively small drop in temperature occurs in the heated air as it passes through the parallel streams of grain flowing downwardly in passages 64, 66. There will be some cooling and moisture accumulation-in the drying air as it passes radially outwardly through the parallel streams of grain, however, it will be observed that the grain traveling along paths 68, 69 adjacent side wall 16 will travel a longer path than the grain traveling closer to duct 60. Thus, the portions of grain subjected to relatively higher temperature, dryer air will pass through upper enclosure 12 in a shorter period of time than the portions of grain subjected to the relatively cooler and wetter air will be subjected thereto for a longer period of time thereby tending to equalize the overall drying effect on all the grain passing through the apparatus. As the grain reaches the lower extremities of upper drying enclosure 12 and enters discharge opening 74, the two streams of grain following paths 68, 69 are maintained in separate, segregated paths and mixing or co-mingling is prevented by divider plate 136.

As the grain progresses downwardly through discharge opening 74 in upper enclosure 12 and enters inlet opening 83 in lower enclosure 80, the two separate, parallel streams of grain are maintained in' passages 86, 88 by duct 84, as shown by arrows 92, 93. Simultaneously, cool air is forced into duct 84 by blower 144 and is forced outwardly through passages 86, 88 and through the parallel streams of grain flowing down wardly therein, the radial distance which the cooling air must traverse passing through the two, parallel streams of grain 92, 93 being relatively short. Further, it will be apparent that as the cooling air passes readially outwardly through the grain, it will accumulate moisture and heat from the warm grain. Again, the grain in the separate, parallel streams 92, 93 moving adjacent duct 84 will follow a shorter path than the grain moving adjacent side wall 80 thus tending to equalize the drying and cooling effect of the cooling air on the grain passing through passages 86, 88. The dried grain in the two parallel streams 92, 93 is maintained in a completely separate state by divider plate 98.

As the grain in the two, separate, parallel streams 92, 93 approaches discharge openings 104, 106, it is subjected to a final flow of cooling air which passes downwardly through openings 160 in duct 84 between skirts 157, 159 and divider plate 98.

The two, parallel, separate streams of dried grain 92, 93 are separately discharged through discharge openings I04, 106 under the control of metering rolls 126 and separately discharged to unloading augers 112.

While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

What is claimed is:

1. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top end and an open bottom end, means for introducing grain to be dried to said upper enclosure adjacent said top end for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, means communicating with said first duct means for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, divider means connecting said first and second duct means and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages. means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being discharged to the atmosphere, said heating and cooling air flows being in parallel, first and second discharge openings in the side wall of said second duct means for respectively separately discharging said streams from said second passages, an imperforate divider plate extending downwardly from said second duct means between said discharge openings for separately discharging said streams from said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, a pair of skirt elements depending from said second duct means wall in spaced parallel relationship with said divider plate, said lastnamed openings respectively communicating with the spaces between said skirt elements and divider plate, said skirt elements being shorter than said divider plate whereby said second streams are respectively subjected to a final flow of cooling air as they are discharged.

2. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top and an open bottom end, means for introducing grain to be dried to said upper enclosure adjacent said top end for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, said upper enclosure and said first duct means being generally cylinderical in crosssection, means communicating with said first duct means for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed, foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, said lower enclosure being generally diamondshaped in cross section and having an apex at its bottom end, said second duct means being generally diamond-shaped in cross-section and having apices at its top and bottom ends, a first imperforate divider plate extending between the top apex of said second duct and said first duct and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages, means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being discharged to the atmosphere, said heating and cooling air flows being in parallel, a second imperforate divider plate extending between the bottom apices of said second duct and lower enclosure, discharge openings respectively formed in the side walls of said lower enclosure adjacent its bottom apex and on opposite sides of said second divider plate for respectively separately discharging said streams from said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, a horizontal plate member connected to the bottom apex of said lower enclosure and having sid edges respectively spaced on opposite sides thereof, metering rolls respectively disposed adjacent said discharge openings on opposite sides of said bottom apex and over said plate member for respectively metering grain discharged through said discharge openings from said second passages, trough elements respectively connected to said opposite sides of said plate member and respectively having first and second unloading augers therein for respectively receiving grain from said first and second metering rolls, and flow control gates for respectively selectively adjusting the size of said discharge openings.

3. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top end and an open bottom end, means including a hopper communicating with said top end for introducing grain to be dried to said upper enclosure for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, means communicating with said first duct means'for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed, foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, first divider means connecting said first and second duct means and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages, means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being discharged to the atmosphere, said heating and cooling air flows being in parallel, first and second discharge openings in the side wall of said lower enclosure respectively communicating with said second passages for separately discharging said streams therefrom, second divider means extending downwardly from said second duct means between said first and second openings for completing separation of said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, first and second metering rolls respectively disposed on opposite sides of said second divider means for respectively metering therein. 

1. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top end and an open bottom end, means for introducing grain to be dried to said upper enclosure adjacent said top end for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, means communicating with said first duct means for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, divider means connecting said first and second duct means and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages, means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being disCharged to the atmosphere, said heating and cooling air flows being in parallel, first and second discharge openings in the side wall of said second duct means for respectively separately discharging said streams from said second passages, an imperforate divider plate extending downwardly from said second duct means between said discharge openings for separately discharging said streams from said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, a pair of skirt elements depending from said second duct means wall in spaced parallel relationship with said divider plate, said last-named openings respectively communicating with the spaces between said skirt elements and divider plate, said skirt elements being shorter than said divider plate whereby said second streams are respectively subjected to a final flow of cooling air as they are discharged.
 1. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top end and an open bottom end, means for introducing grain to be dried to said upper enclosure adjacent said top end for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, means communicating with said first duct means for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, divider means connecting said first and second duct means and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages, means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being disCharged to the atmosphere, said heating and cooling air flows being in parallel, first and second discharge openings in the side wall of said second duct means for respectively separately discharging said streams from said second passages, an imperforate divider plate extending downwardly from said second duct means between said discharge openings for separately discharging said streams from said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, a pair of skirt elements depending from said second duct means wall in spaced parallel relationship with said divider plate, said last-named openings respectively communicating with the spaces between said skirt elements and divider plate, said skirt elements being shorter than said divider plate whereby said second streams are respectively subjected to a final flow of cooling air as they are discharged.
 2. Continuous flow grain drying apparatus comprising: an upper, foraminous drying enclosure having a top and an open bottom end, means for introducing grain to be dried to said upper enclosure adjacent said top end for downward gravity flow therethrough, first, enclosed, foraminous duct means in said upper enclosure for defining therewith a first pair of passages therein thereby dividing said downward flow into two separate, parallel streams, said upper enclosure and said first duct means being generally cylinderical in cross-section, means communicating with said first duct means for causing an outward flow of heated air simultaneously through said first passages, a lower foraminous cooling enclosure having an open top end connected to said bottom end of said upper enclosure and having a bottom end, second, enclosed, foraminous duct means in said lower enclosure for defining therewith a second pair of passages therein, said lower enclosure being generally diamond-shaped in cross-section and having an apex at its bottom end, said second duct means being generally diamond-shaped in cross-section and having apices at its top and bottom ends, a first imperforate divider plate extending between the top apex of said second duct and said first duct and extending through said open ends of said enclosures for coupling respective ones of said first and second passages whereby said two streams respectively continue separate, downward, parallel flow through said second passages, means communicating with said second duct means for causing an outward flow of cooling air simultaneously through said second passages, said cooling air flow being discharged to the atmosphere, said heating and cooling air flows being in parallel, a second imperforate divider plate extending between the bottom apices of said second duct and lower enclosure, discharge openings respectively formed in the side walls of said lower enclosure adjacent its bottom apex and on opposite sides of said second divider plate for respectively separately discharging said streams from said second passages whereby said two streams are maintained separate without co-mingling throughout their downward flow through said apparatus, a horizontal plate member connected to the bottom apex of said lower enclosure and having sid edges respectively spaced on opposite sides thereof, metering rolls respectively disposed adjacent said discharge openings on opposite sides of said bottom apex and over said plate member for respectively metering grain discharged through said discharge openings from said second passages, trough elements respectively connected to said opposite sides of said plate member and respectively having first and second unloading augers therein for respectively receiving grain from said first and second metering rolls, and flow control gates for respectively selectively adjusting the size of said discharge openings. 